화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.104, No.29, 6777-6784, 2000
Laser ablation of graphite-Co/Ni and growth of single-wall carbon nanotubes in vortexes formed in an Ar atmosphere
To study the Nd:YAG laser ablation of graphite-Co/Ni (1.2 at. %) and the growth of single-wall carbon nanotubes (SWNTs) in an Ar atmosphere at 1200 degrees C, we applied time-resolved imaging and spectroscopic techniques. These techniques are based on measuring the laser plume emission and light scattering of growing materials. Laser ablation was performed at a fluence of 1.7 J/cm(2) at 1200 degrees C and at room temperature for comparison. At 1200 degrees C, we observed temporally and spatially dependent emissions of C, C-2, Co, Ni, and Ar species. In addition, emission, probably due to hot clusters and/or particles grown through the interaction with Ar atoms, could be seen at up to 1.5 ms. This emission showed the images separating into two regions at > 100 mu s; resulting from the formation of vortexes. In the light scattering images at 2-1000 ms after 1200 degrees C ablation, we observed the vortexes propagating forward (about 7 cm from the target) during 200 ms and then flowing downward to the target. We suggest that the time available for the SWNT growth in the vortexes is from a few milliseconds to the order of 1 s.